This invention relates to a system and method for attempting to complete a call, while at least one call is in progress, between a subscriber premises and telephone network where the subscriber premises is connected by a single point-of-attachment having a single phone number using an analog interface.
Multiple calls often are established over digital networks from terminals connected by a point-of-attachment identified by a single terminal number. For example, networks using packet-switched data networks, described in ITU-T recommendations X.25, use digital terminations and allow multiple calls over the network. Other examples include frame-relay networks, described in ITU-T recommendation I.233; narrow-band ISDN, described in ITU-T recommendation I.210; and broad-band ISDN networks, described in ITU-T recommendation I.211. These services use digital terminations that can be expensive to implement and maintain.
It would be advantageous if a premises connected by a point-of-attachment to the public switched Telephone Network (PSTN) having a single phone number for handling voice calls with the standard, analog xe2x80x9ctip-and-ringxe2x80x9d interface could carry a modulated signal between the premises and the public switched telephone network that includes multi-call capability from terminal equipment located on the premises, such as a telephone, video, fax machine, or computer. This would be advantageous, for example, if someone at a premises is using a computer while at the same time a telephone call needs to be made to a different location. Other examples could include someone making two telephone calls to the network, or using a computer and fax machine or a telephone and fax machine simultaneously.
It is therefore desirable if a method and system could attempt to complete a call, while at least one call is in progress, using terminal equipment which is connected by a point-of-attachment having a single phone number to a public switched telephone network without digital termination such as ISDN systems.
The present invention now allows a method and system for attempting to complete a call using terminal equipment, while at least one call is in progress, which is connected by a point-of-attachment having a single phone number to a telephone network where one dial tone is provided on an analog interface to the premises. The method and system of this invention permits multiple calls, such as an analog phone, video, data, fax and comparable calls over a single analog interface. It can be extended to allow an increased number of calls by utilizing additional analog interfaces. Such an extension, sometimes known as a multi-link arrangement, provides for any allocation of the multiple calls across the plurality of analog interfaces.
In accordance with one aspect of the present invention, a control channel is established between the telephone network, such as a public switched telephone network, and the terminal equipment located at the premises. Calls originating from the premises equipment and the control channel are combined at the premises into a modulated analog signal having a separate channel for each call. Likewise, any incoming calls are combined with the above calls and the control channel for transmission between the customer premises and the public switched telephone network. Identity information is transmitted from the originating terminal equipment through the control channel to aid in determining a remote device with which a call is desired. This includes auxiliary information for progressing the call. The signal is transmitted from a modulation/demodulation device as a modulated analog signal to the public switched telephone network. The modulated analog signal is split into respective calls and the control channel, and the calls are then forwarded to a respective remote device based on identity information and auxiliary information received through the control channel.
In one aspect of the present invention, the calls can be split at the public switched telephone network. The public switched telephone network can also include a cellular network. Identifiers are associated with each channel for distinguishing each channel within the public switched telephone network. Each channel can also comprise a plurality of information blocks, and identifiers can be associated between the public switched telephone network and the terminal equipment for each channel to distinguish the information blocks belonging to each call or control channel.